1. Field of Use
This invention relates generally to a two-piece re-usable plastic fastener for releasably securing two panels together in spaced-apart predetermined fixed relationship.
In particular, it relates to such a fastener which is especially well-adapted for use in securing one panel, such as an electronic circuit board, to another panel, such as another circuit board or a sheet metal panel forming part of the chassis of electronic equipment.
2. Description of the Prior Art
In some electrical or electronic equipment, for example, it is necessary to secure one planar member or panel, such as an electronic circuit board, in spaced-apart predetermined fixed relationship either to the sheet metal chassis in the equipment or to another circuit board. In some cases two or more circuit boards, which have printed or wired circuitry and electronic components thereon, are disposed in stacked arrangement. Typically, the boards are assembled and mechanically secured together and to a chassis by means of a plurality of elongated bolts (metal or plastic) which extend through drilled or punched aligned holes near the edges of the circuit boards and proper spacing between adjacent boards and between a board and the chassis (to ensure electrical isolation and clearance for board components) is achieved by means of hollow cylindrical bushings (metal or plastic) which are slipped onto the bolts as the assembly progresses. Nuts are screwed onto the ends of the bolts to complete the assembly. Or, in some cases, instead of bushings, sets of nuts may be screwed onto a bolt as each board is emplaced on the bolt to ensure desired spacing, rigidity and fixed positioning. Removal and replacement of circuit boards which are so assembled involves similar steps. Needless to say, use of the above-described prior art means and methods is time-consuming, costly and requires attention and care to insure precise spacing.